A release fluid delivery rate is an important parameter to consider for print jobs using a printing system such as, e.g., a ink jet printing system or xerographic printing system. For example, fluid applicators may be designed to supply release fluid such as, for example, silicone oil to a fuser member, at a nominal rate. The nominal rate may not be easily adjusted. Such systems are vulnerable to release fluid variability due to system component variations and wear, as well as demands introduced by various media types.
A given media and/or job type may have a corresponding optimum fluid release rate. For fixed rate release fluid delivery systems, the rate must be chosen so that the most demanding requirements within a print job are met. Consequently, for a print job having multiple media types of varying demands, for example, the least demanding media types nonetheless receive release fluid at a rate suitable for the most demanding media types. Excess release fluid may cause prints to become oily, and/or objects to fail to stick to paper, and/or excess release fluid spreading to other components of the printing system such as in duplexing operations. Too little release fluid may degrade image quality and increase a difficulty of removing the sheet from a fusing member, such as a fuser roll that defines a fusing nip with a backing member. Too little release fluid may shorten the life of fusing and/or spreading rolls.
A release fluid metering rate may be adjusted as appropriate for particular media types and/or print job demands. For example, related art systems include ink jet printing systems and xerographic printing systems as described in “Variable Fuser Release Fluid Application” (U.S. application Ser. No. 12/243,380) to Derimiggio et al. Such systems accommodate metering release fluid onto a fuser roll surface at various rates depending on a surface velocity of a fluid film metering roll, and at least one of an amount of fluid film left on a the donor roll, a film thickness of the fluid film on the fluid film metering roll, and a speed ratio between the fluid film metering roll and the donor roll. A variable speed drive operably connected to the metering roll may be used to adjust the release fluid metering rate according to particular print job requirements. A closed loop oil rate control system as disclosed in “Passive IR Oil Rate Sensor” (U.S. application Ser. No. 12/352,136) to Dermiggio may be used to adjust a release metering rate toward a desired metering rate by, e.g., monitoring release film thickness using an IR sensor and connected controller.